1. Field of the Invention
The present invention relates to a UTOPIA (Universal Test & Operations Physical layer Interface for ATM (Asynchronous Transfer Mode)) interface, and more particularly, to a method for controlling cell transmission on a basis of 1-byte between FIFOs (First-In-First-Out) of a UTOPIA interface, in order to perform cell transmission faster and more smoothly by defining an active timing of a cell enable signal and a cell available signal between FIFOs of the UTOPIA interface as when 1-byte of data is present.
2. Description of the Related Art
In general, the data transmission mode of a UTOPIA interface in an asynchronous transfer mode (ATM) can be divided into two kinds: Cell-level handshaking mode and Octet-level handshaking mode. In the cell-level handshaking mode, data is transmitted in a 53-byte unit (cell unit) and in the octet-level handshaking mode data is transmitted in an 8-bits unit (octet unit).
In data transmission between FIFOs of the UTOPIA interface that is primarily performed in the cell-level handshaking mode, in reality, however, when a cell is stored in or outputted from the FIFO, a 53-byte cell is piled up in the FIFO or outputted from the FIFO successively. For instance, it is least likely to happen that only 20 bytes out of 53 bytes of a cell are stored first and the remaining 33 bytes are stored after a short interruption.
Therefore, when cell data transmission is controlled according to the related art, the TX FIFO (transmit First-In-First-Out) has to wait until all of the 53 bytes are stored while the RX FIFO (receive First-In-First-Out) has to wait until storage for a 53-byte data is created, thereby wasting as much as 53 bytes*clock.